//The MIT License

//Copyright (c) 2009 Lluis Sanchez, Nick Darnell

//Permission is hereby granted, free of charge, to any person obtaining a copy
//of this software and associated documentation files (the "Software"), to deal
//in the Software without restriction, including without limitation the rights
//to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//copies of the Software, and to permit persons to whom the Software is
//furnished to do so, subject to the following conditions:

//The above copyright notice and this permission notice shall be included in
//all copies or substantial portions of the Software.

//THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//THE SOFTWARE.

using System;
using System.Reflection;
using System.Reflection.Emit;
using Polymorph.Properties;

namespace Polymorph
{
    /// <summary>
    /// The <see cref="CodeIf"/> class represents a if statement.
    /// </summary>
    public class CodeIf : CodeStatement
    {
        private CodeExpression m_condition;
        private CodeBlock m_trueBlock;
        private CodeBlock m_falseBlock;

        /// <summary>
        /// Initializes a new instance of <see cref="CodeIf"/> with the conditional
        /// expression to evaluate.
        /// </summary>
        /// <param name="condition">The condition to test in the expression.</param>
        public CodeIf(CodeExpression condition)
        {
            m_condition = condition;

            if (condition.ResultType != typeof(bool))
            {
                throw new ArgumentException(String.Format(Resources.ExpMustHave0Result,
                    "bool"), "condition");
            }
        }

        public override void Generate(ILGenerator gen)
        {
            if (m_trueBlock == null)
                throw new InvalidOperationException(Resources.IncompleteIfStatement);

            Label falseLabel = gen.DefineLabel();
            Label endLabel = gen.DefineLabel();

            if (m_falseBlock == null)
            {
                GenerateCondition(gen, endLabel);
                m_trueBlock.Generate(gen);
            }
            else
            {
                GenerateCondition(gen, falseLabel);
                m_trueBlock.Generate(gen);
                gen.Emit(OpCodes.Br, endLabel);
                gen.MarkLabel(falseLabel);
                m_falseBlock.Generate(gen);
            }
            gen.MarkLabel(endLabel);
        }

        void GenerateCondition(ILGenerator gen, Label falseLabel)
        {
            if (m_condition is CodeConditionExpression)
            {
                ((CodeConditionExpression)m_condition).GenerateForBranch(gen, falseLabel, false);
            }
            else
            {
                m_condition.Generate(gen);
                gen.Emit(OpCodes.Brfalse, falseLabel);
            }
        }

        public override void PrintCode(CodeWriter cp)
        {
            if (m_trueBlock == null) return;

            cp.Write("if (");
            m_condition.PrintCode(cp);
            cp.Write(") {");
            cp.EndLine();
            cp.Indent();
            m_trueBlock.PrintCode(cp);
            cp.Unindent();
            cp.BeginLine().Write("}");
            if (m_falseBlock != null)
            {
                cp.EndLine();
                cp.WriteLineInd("else {");
                m_falseBlock.PrintCode(cp);
                cp.Unindent();
                cp.BeginLine().Write("}");
            }
        }

        public CodeBlock TrueBlock
        {
            get { return m_trueBlock; }
            set { m_trueBlock = value; }
        }

        public CodeBlock FalseBlock
        {
            get { return m_falseBlock; }
            set { m_falseBlock = value; }
        }
    }
}